Notes - Section 3.3-3.5

Notes - Section 3.3-3.5 - Avogadros constant: 6.0221421 X...

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Paul Jackman September 22, 2009 Chemistry CHE 106 – M029 Section 3.3-3.5 Notes 3.3 Formula Weights Chemical formulas and chemical equations both have a quantitative significance (subscripts represent precise quantities) Formula and Molecular Weights The formula weight of a substance is the sum of the atomic weights of each atom in its chemical formula. If the chemical formula is that of a molecule, then the formula weight is also called the molecular weight. Percentage Composition from Formulas The percentage by mass contributed by each element in the substance % element= (number of atoms of that element) (atomic weight of element) X 100% Formula weight of compound 3.4 Avogadro’s Number and the Mole In chemistry the unit for dealing with the number of atoms, ions, or molecules in a common-sized sample is the mole
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Unformatted text preview: Avogadros constant: 6.0221421 X 10 23 Molar Mass A mole is always the same number, but has different masses The mass of a single atom of an element (in amu) is numerically equal to the mass (in grams) of 1 mol of that element The mass in grams of one mole of a substance is called the molar mass The molar mass (in g/mol) of any substance is always numerically equal to its formula weight (in amu) Interconverting Masses and Moles Conversions of mass to moles and of moles to mass are frequently encountered in calculations using the mole concept Interconverting Masses and Numbers of Particles Grams use molar mass Moles use Avogadros number Formula units 3.5 Empirical Formulas from Analyses...
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This note was uploaded on 02/09/2010 for the course CHE CHE 106 taught by Professor Korter during the Fall '09 term at Syracuse.

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